Page:The American Cyclopædia (1879) Volume XI.djvu/883

MOSSES 865 cap, called the calyptra ; the nucleus in elon- gating forms a slender bristle, still capped by the calyptra, and when it has attained its full length the portion within the calyptra expands, and forms a capsule (theca, or urn), which is known as the fruit of the moss. The lower portion of the ruptured archegonium remains at the base of the bristle as a vaginula or sheath. In general, a single archegonium only becomes perfect and undergoes these changes. These two distinct kinds of floral organs some- times exist in the same flower and are enclosed in the same perichoetmm, when the moss is called syncecious; if, however, the antheridia occur on one part of the plant and the arche- gonia on another part, the moss is called monoe- cious ; and when each kind of organ occurs on separate plants, the moss is dioecious. The im- portance of these differences in the mosses is apparent from the fact that some species pro- duce in some countries only barren flowers or antheridia, and consequently can never be found there in fruit, a condition always desirable to those who collect for herbariums. It has been well ascertained that where the antheridia are wanting the archegonia never come to perfec- tion ; and there are some dioecious species of hypnum, for instance, which are usually desti- tute of capsules from that cause. The cap- sule, sporangium, or theca of mosses is cellu- lar, has a central axis called the columella, and contains spores. In some instances the sporangium is indehiscent (e. g., phascum) ; in other cases it opens by four lateral valves (andrcea), but in the majority of mosses it opens by means of a lid (operculum). This lid is thrown off when the sporangium is mature. Between the base of the lid and the edge of the mouth of the capsule or sporangium are frequently several rows of large cells forming a sort of ring (annulus), which distend them- selves and assist in the dispersion of the spores. The edge of the mouth of the capsule in some mosses is entire (<?. g., gymnostomum), or it has a fringe (peristome) consisting of .prolonga- tions and divisions of the two inner parietal layers of the capsule. The peristome consists of one or more rows of hygrometric cellular teeth, which are four or some multiple of that number. Where but a single row exists, the mosses are classed as aploperistomi, and where there are double rows as diploperistomi. The teeth are long and twisted together in larbula, or bifurcate in dicranum, or assume a variety of shapes, marking the different genera. In some mosses the inner parietal layer appears as a membrane called the epiphragm or tym- panum, stretched across the mouth from the walls of the sporangium to the columella. ^ The capsule does not always rest in a perpendicular manner upon the seta, but may be inclined to one side, and bent downward or cernuous; and in some mosses one side of it is more de- veloped than the other, producing an unsym- metrical shape. Sometimes there is a consider- able thickening or swelling at its base, to which the name of apophysis is given. The interior of the mature capsule is tilled with a profusion of dust, which however will be found to con- sist of round bodies, which are in fact the spores or seeds. When they have been ejected from the capsule, they are in a condition to grow. From some part of their surface a blad- der-like swelling protrudes, which after a while extends itself by increase of similar ones into a cbnfervoid thread. An entangled mass of such threads soon covers the soil, or the moist surfaces of substances on which the spores have fallen. So much do these threads resem- ble some of the alga, that they were mistaken for them by the earlier botanists. This con- f ervoid vegetation continues from 5 to 20 days, when upon its surface very small buds appear. On examination these buds will be found to be composed of minute scaly leaves ; and thus the axis or future stem is originated at their base. In some genera the moss scarcely de- velops itself beyond this condition, forming its fruit in the interior of the scale-like foliage. In other kinds of mosses the plants grow for a shorter or longer period of time before the inflorescence appears. These conf ervoid threads have been compared to the primordial leaves of the higher orders of plants ; they differ how- ever in this, that on disappearing from the sur- face of the soil, similar threads penetrate it and seem to careless observers to be the roots. In many mosses such seeming roots are pushed from the under side of the stem, or even from the very extremities, in the progress of its growth. Very little is known of the uses of the mosses. In the economy of nature they serve as precursors of the higher plants, ap- pearing first upon sterile places, and collecting among their matted and tufted stems the dust and sand. They afford secure lodging places for insects in winter, as well as food for them in summer. Some species of sphag- num enter largely into the formation of peat bogs ; in these locali- ties the moss continues to grow above while it is constantly decaying below ; a great num- ber of woody plants are found growing with the sphagnum, and these decaying to- gether with the moss .form peat of various qualities. Some bot- anists regard sphag- num as sufficiently dif- ferent from other mosses to form an order I itself (sphagna), intermediate between the true mosses and the liverworts. When first taken from the bog sphagnum is very wet, but if thor- Peat Moss (Sphagnum acutifolium).